I want to be clear that 99% of this blog is just facts and links for further reading. Not until the very end do I share any thoughts.
I am steering away from my emotions, connections, and opinions regarding the recent claims made by RFK Jr. and Donald Trump. So no matter where you, the reader, stand on this issue, I hope my blog can help you understand these complex topics.
Studies regarding Autism Spectrum Disorder (ASD) and Tylenol.
The most recent study, published in 2024, originated from Sweden. This study ultimately concluded that Tylenol does not cause ASD. They followed 2,480,797 people who were born between 1995 and 2019. The last follow-up was completed on December 31st, 2021.
Out of those 2 million plus children 185, 909 were exposed to Tylenol while in the womb. The “crude absolute risk” of developing Autism Spectrum Disorder in the kids who were not exposed was 1.33%. The 185,909 kids who were exposed had a risk of 1.53%. You might be wondering what that actually means, so let me explain.
A crude absolute risk is: “Absolute risk is the probability that an individual who is free of a given disease at an initial age, a, will develop that disease in the subsequent interval (a, t].” 1 This is often used as a tool to help people decide what interventions/actions to take or not to take. This number can also be affected by mortality rates from other diseases/conditions.
Regarding the Swedish study, it is evident that the increased risk associated with those whose mothers took acetaminophen (the generic name for Tylenol) was minimal, at 0.20%. The differences regarding the risk of developing other neurodevelopmental conditions were also looked at: ADHD had a 0.41% higher risk for those exposed to Acetaminophen, and for intellectual disabilities, it was a 0.12% increased risk2.
A factor that was addressed in this study that I personally am grateful about is that they looked to identify any unknown factors. This is called “unobserved confounding:” Meaning anything that could have influenced the results or the actual pregnancies was attempted to be ruled out by comparing pairs of siblings.
What they found by comparing siblings was that there was no evidence that Tylenol exposure caused Autism.
“Acetaminophen Use During Pregnancy and Children’s Risk of Autism, ADHD, and Intellectual Disability”
A 2018 study from Johns Hopkins university looked at umbilical chord blood.
This study analyzed a previous 20-year study from The Boston Birth Cohort that looked at the umbilical cord blood from 996 births. They found that every single umbilical cord had the biomarkers of acetaminophen, and they also checked for 2 common byproducts of acetaminophen. They then separated the results into High, Medium, and Low levels of these biomarkers. They found those with the highest levels were almost three times more likely to have developed ASD than those who had the lowest.
Two crucial points I want to point out to you before you stop reading. First, they did not account for any other variables. Like why was the mother taking Tylenol? Did they have a high fever, which is known to cause neurodevelopmental conditions?
Second, the researchers stated that: “consistent associations between the drug and the disorders across a variety of other factors that correlate with ADHD and autism spectrum disorder diagnoses, such as maternal BMI, preterm birth, child sex, and reports of maternal stressors and substance use.”3
Simply meaning that they also found those conditions to be associated with higher risks at the same time as acetaminophen exposure.
This study showed no causation between Tylenol and ASD, and would warrant further research. The Swedish study is the additional research that was needed.
All previous studies had much smaller sample sizes: one in 2008 was just a review of parents’ self-reporting if their child was diagnosed with ASD after getting the MMR vaccine and was given Tylenol. The study used the survey results of 83 children who are Autistic and 80 children who were not Autistic.4
On average, they were asked to recall this information 6 years after the incident. There was also another study out at the time linking Acetaminophen with ASD that was later shown to be fraudulent. 5
Right away I see a few red flags:
- Psychosocial influence of another (now invalid) study being out at the time of the survey.
- The long time frame between the acetaminophen exposure and when the parents answered the survey
- That the MMR vaccine was also given (which does not cause anyone to be Autistic-that has been thoroughly shown not to be scientifically sound).
- Small sample size
I know it might seem like I am presenting way more facts on “one side” of this “debate,” but that is because one side is way more fact-heavy. The science at this time clearly stands behind ASD not being “caused” by Acetaminophen use of the mother during pregnancy or use after the child is born.
Lecovorin and treating Autism
Something I have seen multiple times is the news media falsely stating that this is chemotherapy or other cancer medications. It is actually commonly given alongside chemo to manage the adverse effects.
More specifically, it is a form of folic acid that is given when other medications, for example Methotrexate interrupt the the bodies ability to absorb folic acid. Essentially because of Lecovorin’s specifical chemical makeup it bypasses an enzyme that methotrexate inhibits and therfore can protect the body from Methotrexate toxicity.6
There have been some limited studies showing preliminary positive results in reducing “symptoms” of ASD. I only found 2 studies. The first study I found, which studied 93 children, explicitly reported improvements in verbal communication.
It also showed that out of the 93 children, 44% had shown either blocking or binding folate receptor antibodies in their cerebrospinal fluid. To not get too detailed, I will summarize this by saying simply that almost half of the kids in the study showed a biomarker that indicated that they might not process or have enough folic acid in their brains. So a high dose of folic acid would make sense to help them.
The other study I found demonstrated a few different ways that Lecovorin could help people with ASD. Mostly those who have a deficency regarding folate. I reccomend this study for more details around why it is believe it could help and overall regarding the current knowledge.
More expansive studies are needing to truly prove Lecovorin’s ability to reduce symptoms of ASD. It is not a cure, and these results have not been reproduced in multiple studies.
Therefore, the current administration is not following the “golden rules” of science they are touting. By reccomending the FDA lable this medication as a treatment for ASD is not telling the whole story and done prematurely.
It is not without side effects and risks.
Here are a few concerns regarding this medications risks, interactions and need for clinical monitoring.
- This medication (and high doses of folic acid in general) can interfere with seizure medications, potentially causing breakthrough seizures.
- Has not been studied in pregnancy, catagory C medication, it is unknown if it is excreted in breast milk.
- We do not know what exactly would need to be monitored when used for ASD, but when used for B12 deficiency, it is recommended to monitor Reticulocyte counts, measure the response to treatment, and serial hemoglobin measurements, measuring indirect bilirubin, LDH, serum iron, and potassium levels can be considered.7
- Allergic reactions
- Insomnia, agitation, depression are psychiatric side effects
- Syncope is a rare neurological side effect.
When I looked on a few sites like Drugs.com in regards to side effects it is mostly known what side effects to experience with methotrexate and other cancer treatments. We really do not know how an otherwise healthy autistic child would react to this medication.
It is seeming like it could be helpful, but I caution individuals to discuss risk vs. benefits with their providers and consider the autistic’s quality of life. Not the burnden on a teacher or family member as factor in deciding to use this currently off-label treatment.
So Is RFK Jr. Right?
When it comes to Acetaminophen causing Autism, no he is not right. The larger scientific community disagrees with him. So far as of 3am Tuesday 9/23/25 (ET) the White House has refused to release the data and studies used to make these claims.
When it comes to using Lecovorin to treat symptoms of ASD. I cannot give a simple yes or no answer. It is early on in this research, so what we have so far shows a possible benefit. But it is not clearly identified, treatment protocols have not been established, and if it were any other medication, RFK Jr. would be saying it was approved too early.
My thoughts, because I feel my unique position as an Autistic and ADHD RN who also has worked with Autistic people counts for something.
Firstly, I feel like the HHS secretary was looking for an easy scapegoat, completely ignoring the genetic component of Autism and the complexity of the neurotype.
The language they continue to use about autistic individuals is ableist and cruel.
Kennedy has a long history of anti-science and anti-vaccine beliefs. Look up the deadly impacts of his visit and the spread of anti-vaccine skepticism in Samoa caused.
There is a long history of blaming mothers for causing their child to be autistic. In the early 20th century, the term “refrigerator mothers” was commonplace. Falsely claiming that the only pain and fever-reducing medication safe to take during pregnancy causes harm to the mother and potentially the fetus. It also points a finger unjustly at mothers for taking this medication.
No science to prove this statement: Those “refrigerator mothers” could easily have been autistic themselves and bonded differently than a neurotypical doctor expected. Just saying it is something to consider. Not that they were the genuine cause, but rather reflecting the mindset of the time.
Is science perfect? Is medicine perfect? NO! Do I blindly trust drug manufacturers to be honest at all times? NO! Do I trust multiple studies showing time and time again that there is no causal link between things? YES!
A picture of the author wearing glasses and her hair pulled back. She is wearing a pale green scrub top, white flower earrings, and you can see part of her purple stethoscope around her neck.
All this time, trying to cure, prevent, or decrease the visibility of Autism could have been spent building better support systems in the community.
That is where I will always get so upset at this deficit-based mindset around Autistic people. It forgets there are people, Autistic people, who need support. Those who, if given that support, could have fuller and possibly easier lives.
Please do not buy into this hype. It is not there to help Autistics; it is more to create real-life clickbait. It scares me regarding the future of healthcare in the US.
- https://academic.oup.com/biostatistics/article-abstract/6/2/227/242272?redirectedFrom=PDF ↩︎
- https://pubmed.ncbi.nlm.nih.gov/38592388/ ↩︎
- https://hub.jhu.edu/2019/11/05/acetaminophen-pregnancy-autism-adhd/ ↩︎
- I hesitate to even link to this study because of the issues I found with it. But again, this is not about me or my feelings, thoughts, or beliefs. I want to present you with information. That being said, I would not take the results seriously. ↩︎
- https://www.nbcwashington.com/news/national-international/fact-check-claims-autism-tylenol-folate/3990643/#:~:text=Among%20other%20issues%2C%20the%20researchers,causes%20autism%2C”%20Alwan%20said. ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK553114/ ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK553114 ↩︎
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